•试图向设备在Firebase数据库中拥有的所有用户发送通知，但在云功能的寄存器中显示：“ ReferenceError：未定义值”。

应该做的是：每次在“通知”中进行更改时，您都必须获取已更改的数据，并在设备表中查找此数据，然后向其中的所有令牌发送通知。设备。

这是错误：

cloudfunction的代码：

const functions = require('firebase-functions');
const admin = require('firebase-admin');  // this is the Admin SDK,not firebase-functions

admin.initializeApp(functions.config().firebase);

const db = admin.database()
const ms = admin.messaging()

exports.notifications = functions.database.ref('Notifications/{id}').onUpdate(async(evt) =>{

const payload = {
    notification:{
        title   : 'Alarma se activó tu cerca',body    : 'Se activó tu cerca,revisala',badge   : '1',sound   :'defaul'   
    }
};

//Get Notification Device ID
const notysnap = await db.ref('Notification/').once('value');

var devicee = notysnap.notty;
var dev = JSON.stringify(devicee);

//Get number of users that the device had
const userssnap = await db.ref('Devices/'+ dev + '/Users').once(value)
const nUsers = userssnap.nUsers;
var Nusers = JSON.stringify(nUsers);
var nNUsers = parseInt(Nusers);

//Send notification to the number of users that exist
if (Nusers !== null){
    for(i = 1; 1 <=nNUsers; i++){
        if(i === 1){
            const userToSendP1 = userssnap.user1;
            var userToSend1 = JSON.stringify(userToSendP1);
            Console.log("Mensaje enviado a user 1");
            return ms.sendToDevice(userToSend1,payload);
        }else if(i === 2){
            const userToSendP2 = userssnap.user2;
            var userToSend2 = JSON.stringify(userToSendP2);
            Console.log("Mensaje enviado a user 2");
            return ms.sendToDevice(userToSend2,payload);
        }else if(i === 2){
            const userToSendP3 = userssnap.user3;
            var userToSend3 = JSON.stringify(userToSendP3);
            Console.log("Mensaje enviado a user 3");
            return ms.sendToDevice(userToSend3,payload);
        }else if(i === 2){
            const userToSendP4 = userssnap.user4;
            var userToSend4 = JSON.stringify(userToSendP4);
            Console.log("Mensaje enviado a user 4");
            return ms.sendToDevice(userToSend4,payload);
        }
    }
}
return null
})

数据库：